Proteome analysis of aniline-induced proteins in Acinetobacter lwoffii K24

Acinetobacter lwoffii K24 is a soil bacterium that can use aniline as a sole carbon and nitrogen source (by beta-ketoadipate pathway genes (cat genes)) and has two copies of catABC gene separately located on the chromosome. In order to identify aniline-induced proteins, two-dimensional electrophoresis (2-DE) was applied to soluble protein fractions of A. lwoffii K24 cultured in aniline and succinate media. In the range of pH3-10, more than 370 spots were detected on the silver stained gels. Interestingly, more than 20 spots were selectively induced on aniline-cultured bacteria. Twenty-three protein spots of A. lwoffii K24 were analyzed by N-terminal microsequencing and internal microsequencing with in-gel digestion. Of 20 aniline induced protein spots, we identified six beta-ketoadipate pathway genes, one subunit of amino group transfer (putative subunit of aniline oxygenase), malate dehydrogenase, putative ABC transporter, putative hydrolase, HHDD isomerase, and five unknown proteins. Especially in case of two catechol 1,2-dioxygenases (CDI1 and CDI2), more than three isotypes were detected on the 2D gel. This study showed that the proteome analysis of A. lwoffii K24 may be helpful for identification of genes induced by aniline and understanding of their function in the cell.